THE MAST CELLS 



mast cells around capillaries; Neumann (1885) and Staemmler (1921) saw them 

 more frequently around small arterioles and venules. Jorpes, Holmgren and 

 Wilander (1937) describe mast cells around the vessels of the choroid and at 

 the limbus of the eye. In a statistical survey of mast cells in the adventitia 

 of the larger blood vessels Sundberg (1955) found a rise in mast-cell content up 

 to middle life, most marked in the aorta, followed by a decisive fall, especially 

 in the walls of the large veins. 



The central nervous system of man resembles that of most other species 

 in lacking mast cells (Harris, 1900; Squartini and Giacanelli, 1956) though 

 they occur in the meninges (Rosenheim, 1886) and even in connective tissue 

 around the vessels of the choroid plexuses (Tsusaki, 1951) and pituitary 

 stalk (Gray, 1935; Consolandi and Briziarelli, 1952). Outside the central 

 nervous system the cells are comparatively common in the sheaths of peripheral 

 nerves (Henschen, 1928) though rare in and around autonomic ganglia 

 (Hermann, 1952). 



The general conclusion to be drawn from this preliminary survey of the 

 distribution of the mast cells in man and in the rat is that they are, as Ehrlich 

 stated, cells of the loose connective tissue. As Staemmler (1921) points out, 

 their presence in a parenchymatous organ can usually be accounted for by its 

 connective tissue content, the exceptions, apparently, being thymus and, to 

 a lesser extent, lymph nodes in which the mast-cell content increases with hyper- 

 trophy of the parenchyma. The special relationship of the mast cells to the 

 lymphoid tissue has been considered above: further examples of the association 

 of mast cells with connective tissue and its possible significance will be discussed 

 when the mast-cell content of pathological tissues is examined. Meanwhile, we 

 may complete our survey of the normal organism by reviewing briefly the second 

 type of mast cell in the vertebrates, the blood mast cell, basophil or mast 

 leucocyte. 



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